Not so Blooming Forsythia

When you say cut back do you mean right back into old hard wood stems? As you probably realise now forsythia flowers on new growth from previous year.ie any new green shoots this year will carry next years flowers.The stems that flower this year will not flower next year but bear new growth that will.Subsequently if pruning missed they get tall and leggy only bearing flowers at the top.If done at wrong time and into new growth next years flower stems have been removed.
If you have new growth that has not flowered leave till next spring and when finished flowering cut back to shape.

It was very old and growing wild so I cut back old wood and new wood. It has not flowered since! It turns green every year, but this year I have maybe 10 flowers in all, all over the bush! It doesn't bloom like any forsythia I have ever seen. I also have a hygrenga that gets enormous each year but has yet to bloom. It gets new growth from the bottom, have never seen budding on old wood.